Since the early days of society there has been a significant need to positively identify persons, to grant or deny them access to places, information, property etc. With the advent of modern technologies, the ability of even a single person to collect information, cause damage or affect events has increased exponentially, making it more important than ever to positively ensure that someone really is who he or she claims to be. Additionally, it is also important to identify unknown persons, for example to determine whether they may be of interest to security or law enforcement organizations.
The importance and value of identification systems cannot be overstate. In addition to addressing the better known national security issues such as espionage, sabotage etc, more recent concerns over terrorism and industrial espionage have demanded fast and accurate methods of identification, which cannot easily be defeated by a determined opponent. These methods are useful not only to secure access to physical locations, such as military, governmental and industrial sites, but also to limit access to information stored in electronic devices such as computers, which may be connected to worldwide networks.
Identification cards and access codes have been used to identify persons and to grant access, but they have severe limitations. Cards can be lost, stolen or forged, and codes/passwords can be forgotten or obtained by the wrong persons. Biometrics provides a solution to these issues. Biometrics is the statistical observation and measurement of biological phenomena, such as the characteristics that differentiate one person from another. These biometric characteristics are used to identify and validate someone's identity. Perhaps the oldest form of biometric identification involves comparing fingerprints of a person to known fingerprints. This method can be very accurate, but is often time consuming if done manually, and resource intensive if carried out by machine. In addition, imperfect fingerprints due to contamination or injury of the fingers or to a partial fingerprint make the comparison problem even more difficult.